US8258673B2 - Semiconductor device and method of fabricating the semiconductor device - Google Patents
Semiconductor device and method of fabricating the semiconductor device Download PDFInfo
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- US8258673B2 US8258673B2 US12/817,674 US81767410A US8258673B2 US 8258673 B2 US8258673 B2 US 8258673B2 US 81767410 A US81767410 A US 81767410A US 8258673 B2 US8258673 B2 US 8258673B2
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Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
- B81B3/0064—Constitution or structural means for improving or controlling the physical properties of a device
- B81B3/0086—Electrical characteristics, e.g. reducing driving voltage, improving resistance to peak voltage
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
- G01C19/5719—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using planar vibrating masses driven in a translation vibration along an axis
- G01C19/5733—Structural details or topology
- G01C19/5755—Structural details or topology the devices having a single sensing mass
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
- G01C19/5719—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using planar vibrating masses driven in a translation vibration along an axis
- G01C19/5769—Manufacturing; Mounting; Housings
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
- G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
- G01P15/125—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by capacitive pick-up
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B2203/00—Basic microelectromechanical structures
- B81B2203/01—Suspended structures, i.e. structures allowing a movement
- B81B2203/0118—Cantilevers
Definitions
- the present invention relates to a semiconductor device including a beam-type oscillator, and to a method of fabricating the semiconductor device.
- a semiconductor device such as a micro electro mechanical system (MEMS) device including a beam-type oscillator, a surface acoustic wave (SAW) device and a film bulk acoustic resonator (FBAR) using a piezoelectric material is used for an acceleration sensor, a gyro sensor and the like.
- MEMS micro electro mechanical system
- SAW surface acoustic wave
- FBAR film bulk acoustic resonator
- an electrostatic capacitance type acceleration sensor that detects an acceleration by sensing a change of electrostatic capacitance between an oscillator as a movable electrode and a fixed electrode fixed to a substrate, and the like are put into practical use.
- the oscillator that has oscillated sometimes contacts the semiconductor substrate located below the oscillator.
- an insulating film is not arranged on a lower surface of the oscillator, the oscillator and the semiconductor substrate electrically short-circuit with each other, are fixedly adhered to each other, and so on. Therefore, a method of covering the entire periphery of the oscillator with the insulating film is proposed (for example, refer to Patent Literature 1).
- the semiconductor substrate to which the oscillator having the entire periphery thus coated with the insulating film is fixed is pasted to an opposite substrate, whereby a semiconductor device is fabricated.
- a semiconductor device which includes: a semiconductor substrate, in which a recessed portion is formed on an upper surface, and a semiconductor layer is exposed to a bottom surface of the recessed portion; an oscillator that has a beam-type movable electrode arranged in the recessed portion so as to be opposed to a surface of the semiconductor layer, the movable electrode having insulating films arranged on side surfaces and lower surface thereof, and is fixed to the semiconductor substrate at a position apart from the movable electrode; and a beam-type fixed electrode that is arranged in the recessed portion so as to be opposed to the movable electrode and the surface of the semiconductor layer, and is fixed to the semiconductor substrate so as to be electrically isolated from the movable electrode.
- a method of fabricating a semiconductor device including an oscillator that has a movable electrode, and a fixed electrode fixed to a semiconductor substrate so as to be opposed to the movable electrode includes the steps of: stacking a lower semiconductor layer, an interlayer insulating layer and an upper semiconductor layer on one another, and forming the semiconductor substrate; forming a side trench by etching a part of the upper semiconductor layer, and exposing side surfaces of the oscillator and the fixed electrode; forming a side insulating film on the side surfaces of the oscillator and the fixed electrode; removing the interlayer insulating layer exposed to a bottom portion of the side trench, exposing a surface of the lower semiconductor layer, and leaving, as lower insulating films, the interlayer insulating layer located on lower surfaces of the oscillator and the fixed electrode; and etching a part of an upper surface of the lower semiconductor layer by isotropic etching using the side insulating film and the lower insulating films as mask
- the semiconductor device in which the short circuit between the oscillator and the semiconductor substrate is prevented, the semiconductor device being capable of suppressing the increase of the fabrication steps, and to provide the method of fabricating the semiconductor device.
- FIG. 1 is a schematic plan view showing a configuration of a semiconductor device according to an embodiment.
- FIG. 2 is a schematic cross-sectional structure view along a line I-I of FIG. 1 .
- FIG. 3 is a schematic cross-sectional structure view along the line I-I of FIG. 1 , in which a cover film is further provided.
- FIG. 4 is a schematic plan view showing a configuration of the semiconductor device according to the embodiment, in which a signal processing circuit mounting portion is provided on a peripheral portion.
- FIG. 5 is a schematic cross-sectional structure view along a line II-II of FIG. 1 .
- FIG. 6 is a schematic cross-sectional structure view along a line III-III of FIG. 2 .
- FIG. 7 is a schematic cross-sectional structure view along a line IV-IV of FIG. 4 , showing an example of a schematic cross-sectional structure of a vicinity of a movable electrode and fixed electrode of the semiconductor device according to the embodiment.
- FIG. 8 is a schematic cross-sectional structure view along the line IV-IV of FIG. 4 , showing another example of the schematic cross-sectional structure of the vicinity of the movable electrode and fixed electrode of the semiconductor device according to the embodiment.
- FIG. 9 is a process cross-sectional view for explaining a method of fabricating the semiconductor device according to the embodiment (No. 1).
- FIG. 10 is a process cross-sectional view for explaining the method of fabricating the semiconductor device according to the embodiment (No. 2).
- FIG. 11 is a process cross-sectional view for explaining the method of fabricating the semiconductor device according to the embodiment (No. 3).
- FIG. 12 is a process cross-sectional view for explaining the method of fabricating the semiconductor device according to the embodiment (No. 4).
- FIG. 13 is a process cross-sectional view for explaining the method of fabricating the semiconductor device according to the embodiment (No. 5).
- FIG. 14 is a process cross-sectional view for explaining the method of fabricating the semiconductor device according to the embodiment (No. 6).
- FIG. 15 is a process cross-sectional view for explaining the method of fabricating the semiconductor device according to the embodiment (No. 7).
- FIG. 16 is a process cross-sectional view for explaining the method of fabricating the semiconductor device according to the embodiment (No. 8).
- FIG. 17 is a plan view for explaining the method of fabricating the semiconductor device according to the embodiment.
- FIG. 18 is a process cross-sectional view for explaining another method of fabricating the semiconductor device according to the embodiment, showing a cross section along the line II-II of FIG. 1 in a same process step as in FIG. 12 (No. 1).
- FIG. 19 is a process cross-sectional view for explaining the another method of fabricating the semiconductor device according to the embodiment, showing a cross section along the line II-II of FIG. 1 in a same step as in FIG. 13 (No. 2).
- FIG. 1 A schematic planar configuration of a semiconductor device 1 according to the embodiment is illustrated as shown in FIG. 1 , and a schematic cross-sectional structure along a line I-I of FIG. 1 is illustrated as shown in FIG. 2 .
- the semiconductor device 1 includes: a semiconductor substrate 10 , in which a recessed portion 100 is formed on an upper surface, and a semiconductor layer is exposed on a bottom surface of the recessed portion 100 ; an oscillator 20 that has a beam-type movable electrode 21 arranged in the recessed portion 100 , the movable electrode 21 having insulating films arranged on side surfaces and lower surface thereof, and is fixed to the semiconductor substrate 10 at a position apart from the movable electrode 21 ; and beam-type fixed electrodes 30 which are arranged in the recessed portion 100 so as to be opposed to the movable electrode 21 , and are fixed to the semiconductor substrate 10 so as to be electrically isolated from the movable electrode 21 .
- the oscillator 20 is a beam-type oscillator including: the movable electrode 21 that extends to a center portion of the recessed portion 100 , and is opposed to the fixed electrodes 30 ; and spring portions 22 fixed to the semiconductor substrate 10 at positions apart from positions opposed to the fixed electrodes 30 .
- the oscillator 20 and the semiconductor substrate 10 are connected to each other by the spring-like spring portions 22 having flexibility, whereby it is facilitated for the movable electrode 21 to oscillate. In such a way, detection sensitivity of the semiconductor device 1 is enhanced.
- the oscillator 20 and the semiconductor substrate 10 are connected to each other, whereby two spring portions 22 which meander in an up-and-down direction of a page surface of FIG. 1 . Therefore, the oscillator 20 is likely to oscillate in a right-and-left direction of the page surface, and in accordance with the semiconductor device 1 , external force applied in the right-and-left direction of FIG. 1 is mainly sensed.
- a lower insulating film 50 is arranged on the lower surface of the movable electrode 21 .
- a side insulating film 52 is arranged on the side surfaces of the movable electrode 21 , and an upper insulating film 54 is arranged on an upper surface thereof, whereby the entire periphery of the movable electrode 21 is covered with the insulating films.
- the fixed electrodes 30 have a shape of beams including: fixed ends fixed to the semiconductor substrate at a peripheral portion surrounding the recessed portion 100 ; and free ends extending in the recessed portion 100 .
- lower insulating films 50 are arranged on lower surfaces of the fixed electrodes 30
- the side insulating film 52 is arranged on side surfaces thereof
- the upper insulating films 54 are arranged on upper surfaces thereof, whereby the entire peripheries of the fixed electrodes 30 are covered with the insulating films.
- FIG. 3 A schematic cross-sectional structure along the line I-I of FIG. 1 , in which a cover film 300 is further provided, is illustrated as shown in FIG. 3 .
- FIG. 4 A schematic plan view showing a configuration of the semiconductor device according to the embodiment, in which a signal processing circuit mounting portion 2 is provided on a peripheral portion, is illustrated as shown in FIG. 4 .
- a semiconductor device 1 that composes an acceleration sensor and a signal processing circuit are formed in one chip.
- FIG. 4 shows a plan view of a state where the cover film 300 is detached. Note that the acceleration sensor and the signal processing circuit may be formed in separate chips, and may be formed as a hybrid integrated circuit.
- the cover film 300 is arranged on an upper portion of the semiconductor device 1 while interposing an insulating layer 250 therebetween at the peripheral portion of the semiconductor substrate 10 , whereby the semiconductor device 1 is sealed.
- the recessed portion 100 may be evacuated to vacuum, or nitrogen gas, Ar gas or the like may be hermetically sealed thereinto.
- the insulating layer 250 is a layer for adhering the semiconductor substrate 10 and the cover film 300 to each other.
- a substrate of a semiconductor such as silicon or a substrate of an insulator such as glass is applicable as a material of the cover film 300 .
- FIG. 5 A schematic cross-sectional structure along a line II-II of FIG. 1 is illustrated as shown in FIG. 5
- FIG. 6 A schematic cross-sectional structure along a line III-III of FIG. 2 is illustrated as shown in FIG. 6 .
- an insulating isolation region 40 is formed between the fixed end and free end of the fixed electrode 30 .
- the oscillator is fixed to the semiconductor substrate 10 while interposing insulating isolation regions 40 therebetween.
- the insulating isolation regions 40 the movable electrode 21 and the fixed electrodes 30 are electrically insulated from each other. Therefore, the movable electrode 21 and the fixed electrodes 30 function as capacitor plates.
- the semiconductor substrate 10 is a stacked body of a lower semiconductor layer 11 , an interlayer insulating layer 12 and an upper semiconductor layer 13 .
- a silicon film is adoptable.
- the interlayer insulating layer 12 a silicon oxide (SiO 2 ) film or a stacked body of the SiO 2 film and a silicon nitride (SiN) film is adoptable.
- the silicon film or a polysilicon film is adoptable.
- the recessed portion 100 is formed by partially etching the upper semiconductor layer 13 , the interlayer insulating layer 12 and the lower semiconductor layer 11 . Therefore, a part of the lower semiconductor layer 11 is exposed to a bottom surface 101 of the recessed portion 100 .
- the silicon layer is adopted for the lower semiconductor layer 11 .
- the silicon layer is exposed to the bottom surface 101 of the recessed portion 100 .
- the semiconductor substrate 10 is processed, whereby the oscillator 20 and the fixed electrodes 30 are formed. Then, a part of the upper semiconductor layer 13 is used as the movable electrode 21 and the fixed electrodes 30 .
- apart of the interlayer insulating layer 12 is used as the lower insulating films 50 .
- a position of the oscillator 20 is changed in response to the external force applied to the semiconductor device 1 from the outside, and distances between the movable electrode 21 and the fixed electrodes 30 are changed. Therefore, when the external force is applied to the semiconductor device 1 in a state where a voltage is applied between the movable electrode 21 and the fixed electrodes 30 , changes of the distances between the movable electrode 21 and the fixed electrodes 30 are sensed as a change of electrostatic capacitance.
- the semiconductor device 1 transmits the sensed change of the electrostatic capacitance to a signal processing circuit (not shown) by a detection signal.
- the signal processing circuit processes the detection signal and detects the acceleration caused in the semiconductor device 1 .
- the semiconductor device 1 is a part of an acceleration detection apparatus that detects the acceleration based on the change of the electrostatic capacitance between the movable electrode 21 and the fixed electrode 30 .
- the signal processing circuit may be arranged on the same chip as a chip on which the semiconductor device 1 is arranged, or may be arranged on a different chip from the chip on which the semiconductor device 1 is arranged.
- An electrode wire 61 for transmitting a voltage value of the movable electrode 21 to the signal processing circuit is brought into contact with the oscillator 20 in an opening portion formed by removing a part of the upper insulating film 54 .
- electrode wires 62 for transmitting voltage values of the fixed electrodes 30 to the signal processing circuit are brought into contact with the fixed electrodes 30 in opening portions 620 formed by partially removing the upper insulating films 54 .
- the movable electrode 21 and the fixed electrodes 30 are arranged in an interdigital fashion. In such a way, opposed areas of the movable electrode 21 and the fixed electrodes 30 are increased, and the electrostatic capacitance between the movable electrode 21 and the fixed electrodes 30 is increased. Hence, the acceleration can be detected with high sensitivity.
- widths of the oscillator 20 and the fixed electrodes 30 approximately range, for example, from 3 ⁇ m to 10 ⁇ m, and the distances between the oscillator 20 and the fixed electrodes 30 approximately range, for example, 1 ⁇ m to 2 ⁇ m.
- the movable electrode 21 When the position of the oscillator 20 is changed by the external force, the movable electrode 21 sometimes contacts the bottom surface of the recessed portion 100 .
- the semiconductor layer that composes the semiconductor substrate 10 is exposed to the bottom surface of the recessed portion 100 . Therefore, in the case where the insulating film is not arranged on the lower surface of the movable electrode 21 , the movable electrode 21 and the semiconductor substrate 10 electrically short-circuit with each other, are fixedly adhered to each other, and so on. As a result, a problem occurs that the change of the electrostatic capacitance between the movable electrode 21 and the fixed electrodes 30 cannot be detected accurately.
- the lower insulating film 50 is arranged on the lower surface of the movable electrode 21 . Therefore, even if the movable electrode 21 contacts the bottom surface 101 of the recessed portion 100 , there does not occur the problem that the movable electrode 21 and the semiconductor substrate 10 electrically short-circuit with each other, are fixedly adhered to each other, and so on. Moreover, it is not necessary to form the recessed portion 100 deeply, and accordingly, there does not occur the problem that the movable electrode 21 and the fixed electrode 30 are superposed on each other, either.
- the material and film thickness of the lower insulating film 50 may be selected in consideration of a material, film thickness and the like of the upper insulating film 54 .
- the lower insulating film 50 is arranged on the lower surface of the movable electrode 21 , whereby the semiconductor device in which the short circuit between the oscillator 20 and the semiconductor substrate 10 is prevented can be realized.
- FIG. 7 A schematic cross-sectional structure along a line IV-IV of FIG. 4 , showing an example of a schematic cross-sectional structure of a vicinity of the movable electrode 21 and fixed electrode 30 of the semiconductor device 1 according to the embodiment, is illustrated as shown in FIG. 7 .
- a structure is provided, in which the movable electrode 21 opposed to the fixed electrode 30 is warped downward.
- the movable electrode 21 is formed so that a thickness t 1 of the upper insulating film 54 of the movable electrode 21 can be thicker than a thickness t 2 of a lower insulating film 50 d , whereby the structure in which the movable electrode 21 is warped downward can be formed.
- a possibility that contact between the movable electrode 21 and the cover film 300 can be avoided is increased as compared with the case of FIG. 8 , where the structure in which the movable electrode 21 is warped is not provided.
- FIG. 9 to FIG. 16 are cross-sectional views at the same position as in FIG. 3 .
- the method of fabricating the semiconductor device 1 which is described below, is merely an example, and it is a matter of course that the semiconductor device 1 is realizable by other various fabrication methods including modification examples of the method to be described below.
- the semiconductor substrate 10 with the structure in which the lower semiconductor layer 11 , the interlayer insulating layer 12 and the upper semiconductor layer 13 are stacked on one another is prepared.
- the semiconductor substrate 10 has a structure, in which the interlayer insulating layer 12 with a film thickness approximately ranging from 0.1 ⁇ m to 0.5 ⁇ m is formed on the lower semiconductor layer 11 with a film thickness of approximately 300 ⁇ m, and the upper semiconductor layer 13 with a film thickness approximately ranging from 5 ⁇ m to 100 ⁇ m is stacked on the interlayer insulating layer 12 .
- the lower semiconductor layer 11 is formed of the silicon film
- the interlayer insulating layer 12 is formed of a stacked body of the SiO 2 film and the SiN film
- the upper semiconductor layer 13 is formed of the silicon film.
- the upper insulating film 14 with a film thickness approximately ranging from 0.5 ⁇ m to 2.0 ⁇ m is formed on the semiconductor substrate 10 .
- the SiO 2 film or the stacked body of the SiO 2 film and the SiN film is adoptable.
- a photoresist film 500 is formed on the upper insulating film 14 , and the photoresist film 500 is formed into a desired pattern by using a photolithography technology. Specifically, the photoresist film 500 on a region in which the recessed portion 100 and the insulating isolation regions 40 are formed is removed, and the photoresist film 500 on a region in which the oscillator 20 and the fixed electrodes 30 are formed is left. Then, by selective etching using this photoresist film 500 as a mask, a part of the upper insulating film 14 is removed, and the plurality of upper insulating films 54 are formed on the semiconductor substrate 10 as shown in FIG. 11 . Thereafter, the photoresist film 500 is removed.
- a part of the upper semiconductor layer 13 is removed by etching, whereby a side trench 200 is formed, and the side surfaces of the oscillator 20 and the fixed electrodes 30 are exposed.
- a depth of the side trench 200 is equivalent to the film thickness of the upper semiconductor layer 13 , and for example, approximately ranges from 5 ⁇ m to 100 ⁇ m.
- a Bosch process using a deep reactive ion etching (D-RIE) method is adoptable.
- the side insulating film 52 is formed on a surface of the side trench 200 .
- the side insulating film 52 is formed of an insulating film with a film thickness, for example, approximately ranging from 0.1 ⁇ m to 1 ⁇ m, such as the SiO 2 film and a low pressure tetraethoxysilane (LPTEOS) film as a type of the SiO 2 film.
- the thermal oxidation method and the CVD method are usable for forming the side insulating film 52 .
- (f) Next, as shown in FIG. 14 , by anisotropic etching, the interlayer insulating layer 12 exposed to the bottom surface of the side trench 200 is removed. In such a way, a surface of the lower semiconductor layer 11 is exposed.
- the interlayer insulating layer 12 located on the lower surfaces of the oscillator 20 and the fixed electrodes 30 is left, and the interlayer insulating layer 12 thus left serves as the lower insulating films 50 .
- the upper insulating films 54 are etched simultaneously. Therefore, it is necessary that the film thickness of the upper insulating films 54 be made thicker than that of the interlayer insulating layer 12 .
- a photoresist film is formed on the entire surface of the semiconductor substrate 10 , and thereafter, the photoresist film on regions in which the opening portions 610 and 620 are formed is removed.
- the upper insulating film 54 is removed by etching, whereby the opening portions 610 and 620 are formed.
- the electrode wires 61 and 62 are formed.
- a photoresist film is formed on the entire surface of the semiconductor substrate 10 , and thereafter, the photoresist film on regions in which the electrode wires 61 and 62 are arranged is removed, whereby the photoresist film is formed into a desired pattern.
- FIG. 17 shows a plan view of the semiconductor device 1 in a state where the opening portions 610 and 620 are formed.
- a cross-sectional view along a direction V-V of FIG. 17 corresponds to FIG. 15 .
- the lower surfaces of the oscillator 20 and the fixed electrodes 30 , on which the lower insulating films 50 are arranged, are exposed.
- the lower semiconductor layer 11 is the silicon layer
- an isotropic etcher using sulfur hexafluoride (SF 6 ) gas, and the like are usable.
- the recessed portion 100 is formed on the upper surface of the semiconductor substrate 10 , and the oscillator 20 and the fixed electrode 30 are arranged in the recessed portion 100 .
- the lower semiconductor layer 11 is exposed to the bottom surface 101 of the recessed portion 100 .
- the cover film 300 such as a silicon substrate is arranged on the upper portion of the semiconductor device 1 while interposing the insulating layer 250 therebetween at the peripheral portion of the semiconductor substrate 10 , whereby the semiconductor device 1 is sealed.
- the recessed portion 100 may be evacuated to vacuum, or nitrogen gas, Ar gas or the like may be hermetically sealed thereinto.
- the insulating layer 250 is a layer for adhering the semiconductor substrate 10 and the cover film 300 to each other.
- a material of the insulating layer 250 there is mentioned a glass paste, thermoplastic resin, thermosetting resin, UV curing resin or the like.
- thermoplastic resin for example, there is mentioned resin such as vinyl chloride resin, polyethylene, polypropylene, acrylic resin, polyethylene terephthalate, polyamide, and polycarbonate.
- thermosetting resin there are mentioned epoxy resin, phenol resin, polyurethane resin, melamine resin, and the like.
- UV curing resin there are mentioned acrylic resin, epoxy resin, polyester resin, and the like.
- FIG. 18 corresponds to a schematic cross-sectional structure along the line II-II of FIG. 1 in the same process step as in FIG. 12 .
- the insulating isolation trenches 400 are filled with the insulating film as shown in FIG. 19 , whereby the insulating isolation regions 40 are formed.
- FIG. 19 corresponds to the schematic cross-sectional structure along the line II-II of FIG. 1 in the same process step as in FIG. 12 .
- the side trench 200 may be formed in a different step from that for the insulating isolation trenches 400 .
- the side insulating film 52 and the insulating isolation regions 40 may be formed in different steps from each other.
- the lower insulating films 50 are formed by etching a part of the interlayer insulating layer 12 .
- a material and film thickness of the interlayer insulating layer 12 are arbitrarily settable, whereby the warp amounts and warp directions of the movable electrode 21 and the fixed electrode 30 are adjustable.
- a film structure formed on the upper surfaces of the movable electrode 21 and the fixed electrodes 30 and a film structure formed on the lower surfaces thereof are set the same, whereby the upper surface of the movable electrode 21 and the upper surfaces of the fixed electrodes 30 can be made flush with each other.
- the opposed areas of the movable electrode 21 and the fixed electrodes 30 become the maximum, and the detection sensitivity can be enhanced.
- the material and film thickness of the upper insulating film 54 in response to the desired warp amounts and warp directions of the movable electrode 21 and the fixed electrodes 30 in consideration of the material and film thickness of the upper insulating film 54 arranged on the upper surfaces of the movable electrode 21 and the fixed electrodes 30 .
- the material and film thickness of the interlayer insulating layer 12 are selected appropriately, whereby it is also possible to warp the movable electrode 21 and the fixed electrodes 30 downward toward the bottom surface 101 of the recessed portion 100 .
- the movable electrode 21 is warped downward, whereby the movable electrode 21 can be prevented from contacting the cover film (not shown) that covers the upper portion of the recessed portion 100 .
- the cover film (not shown) that covers the upper portion of the recessed portion 100 .
- the stacked body of the SiO 2 film and the SiN film is adopted for the interlayer insulating layer 12
- the SiO 2 film is adopted for the upper insulating film 14 .
- the semiconductor substrate 10 itself is etched, whereby the oscillator 20 is arranged in the recessed portion 100 . Therefore, a forming step and patterning step of a sacrifice layer for isolating the oscillator 20 and the semiconductor substrate 10 from each other are not required, and an increase of fabrication steps can be suppressed.
- the lower surfaces of the oscillator 20 and the fixed electrodes 30 are covered with the lower insulating films 50 in the isotropic etching for forming the recessed portion 100 . Therefore, the lower surfaces of the oscillator 20 and the fixed electrodes 30 are prevented from being etched in the above-described anisotropic etching. Hence, the oscillator 20 and the fixed electrodes 30 are prevented from being thinned, and the opposed areas of the movable electrode 21 and the fixed electrodes 30 are suppressed from being reduced. As a result, the detection sensitivity is enhanced as compared with a detection apparatus in which the lower insulating films 50 are not arranged on the lower surfaces of the oscillator 20 and the fixed electrodes 30 .
- the lower insulating films 50 are formed on the lower surfaces of the oscillator 20 and the fixed electrodes 50 , whereby a semiconductor device can be provided, in which the short circuit between the oscillator 20 and the semiconductor substrate 10 is prevented, and the increase of the fabrication steps can be suppressed.
- the semiconductor device is applied for the acceleration sensor.
- the usage purpose of the semiconductor device is not limited to the acceleration sensor, and the semiconductor device is usable for a variety of sensors which detect a physical quantity based on the change of the electrostatic capacitance between the movable electrode 21 and the fixed electrodes 30 by using a structure displaced in response to the external force, and the like.
- the present invention is also applicable for an angular velocity sensor, a pressure sensor, a force sensor and the like.
- the semiconductor device of the present invention and the method of fabricating the semiconductor device concerned are usable for an electronic instrument industry including a fabrication industry that fabricates a semiconductor sensor having a movable portion.
Abstract
Description
- Patent Literature 1: Japanese Patent No. 3367113
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Claims (14)
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JP2010119283A JP5520691B2 (en) | 2009-06-18 | 2010-05-25 | Semiconductor device and manufacturing method of semiconductor device |
JPP2010-119283 | 2010-05-25 |
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US8258673B2 true US8258673B2 (en) | 2012-09-04 |
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US8643140B2 (en) * | 2011-07-11 | 2014-02-04 | United Microelectronics Corp. | Suspended beam for use in MEMS device |
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JP5721452B2 (en) * | 2011-01-27 | 2015-05-20 | ローム株式会社 | Capacitive MEMS sensor |
JP5252016B2 (en) * | 2011-03-18 | 2013-07-31 | 横河電機株式会社 | Vibrating transducer |
US9225311B2 (en) | 2012-02-21 | 2015-12-29 | International Business Machines Corporation | Method of manufacturing switchable filters |
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2010
- 2010-05-25 JP JP2010119283A patent/JP5520691B2/en active Active
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JP5520691B2 (en) | 2014-06-11 |
US20100320873A1 (en) | 2010-12-23 |
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